1. Field of the Invention
The present invention relates to an inner rotor type brushless motor which has, for example, a rotor and a stator.
2. Description of Related Art
Generally, an inner rotor type brushless motor has a stator core fitted into and fixed to a stator case and a rotor rotatably provided with respect to the stator core, and includes permanent magnets at an outer peripheral portion thereof. This stator core includes a plurality of teeth which project radially inward. A coil is wound around these teeth. As electric current flows into the coil, an attractive or repulsive force is generated between the rotor and the stator to rotate the rotor.
Among this kind of stator, there is one which includes a plurality of teeth fixed at the internal diameter side of a cylindrical yoke portion, and a coil bobbin coupling body in which a plurality of coil bobbins around which a coil is wound are coupled together, and in which this coil bobbin coupling body is mounted on the teeth (for example, refer to Japanese Patent No. 3190511). Further, there is one in which a dovetail groove is formed at an inner peripheral surface of a yoke portion formed in a tubular shape, and a split tooth including a projection fitted into the dovetail groove is mounted on a coil bobbin around which a coil is wound to form a split core, and is then fitted into the dovetail groove (for example, refer to Japanese Unexamined Patent Application, First Publication No. 2006-296033).
Winding starting end and winding finishing end of the coil wound around the coil bobbin are drawn out to the terminals, and are electrically connected with lead wires drawn in from the outside via the terminals.
FIG. 10 shows a conventional split core.
As shown in this drawing, a split core 118 includes a coil bobbin 160 around which a coil 107 is wound, and a split tooth 161 which is mounted on the coil bobbin 160. The coil bobbin 160 is provided with terminals 180a and 180b which electrically connect the coil 107 wound around the coil bobbin 160 to lead wires drawn from around the outside. Further, the split tooth 161 is a member which is T-shaped in plan view, and one end thereof is formed with a projection 167 which can fit into the aforementioned dovetail groove.
Meanwhile, in the above-mentioned brushless motor, when the coil 107 is wound around the coil bobbin 160, the coil 107 connected to a terminal 180a and the coil 107 wound around the coil bobbin 160 are different from each other in directivity at the winding starting end (at the terminal 180a in FIG. 10) of the coil bobbin 160. Therefore, overlapping coils 107 interfere with each other, and winding of the coil 107 becomes difficult. This causes disordered winding of the coil 107. Thereby, the coil 107 should be mounted (refer to K′ in FIG. 10) while avoiding the winding starting end of the coil 107. As a result, there is a problem in that the occupancy of the coil 107 in the coil bobbin 160 may fall, and the magnetic flux generated from the coil 107 may become small.
As described above, during mounting, a winding starting end of the coil 107 should be avoided. In this respect, there is a problem in that the assembling workability of the stator core is poor.
Therefore, the present invention has been made in view of the above-described situations, and the object of the present invention is to provide a brushless motor capable of cheaply preventing disordered winding of a coil to improve the occupancy of the coil, and easily performing the assembling operation of a stator core.